Saint John, a disciple of Saint Gregory of Decapolis, was born in Isauria and renounced the world from a young age, receiving monastic tonsure from his teacher. He labored alongside him, demonstrating humility and obedience, which delighted Saint Gregory.
During the persecutions against the Church, instigated by the wicked Emperor Leo the Armenian, John, along with Gregory and Saint Joseph the Hymnographer, arrived in Byzantium, strengthening the Orthodox in their faith. After Gregory's death in Rome, John continued his ascetic endeavors in Byzantium.
After Joseph's return from imprisonment, John had already departed to the Lord and was buried near the tomb of Saint Gregory. Joseph, mourning the loss, built a church in honor of Saint Nicholas and transferred the relics of Saints Gregory and John.
Some assert that John, after the death of his teacher, went to Palestine and labored in the monastery of Saint Chariton, but this refers to another saint with the same name. In reality, John lived later, when the monastery of Saint Chariton had already been destroyed.
